An objective atomic structure is a collection of atoms represented by mass points or ions for which every atom sees precisely the same atomic environment, up to rotation (or, more generally, orthogonal transformations) and translation. An objective molecular structure is a collection of molecules in which corresponding atoms in each molecule see precisely the same environment up to orthogonal t...

The crystal structure of bis(ÿ-1,3-cyclohexadiene)monocarbonyliron has been redetermined by X-ray data. The compound crystallizes in the enantiomorphic, orthorhombic space group P212121 with one complete molecule in the asymmetric unit. For concordance to the originally reported structure, which was determined under ambient conditions, the redetermination has been carried out at room temperatur...

The self-assembly of different nanocrystals into a binary superlattice is of interest for both colloidal science and nanomaterials science. New properties may emerge from the interaction between the nanocrystal building blocks that are ordered in close contact in three dimensions. Identification of the superlattice structure including its defects is of key interest in understanding the electric...

Fundamental structural building principles are discussed for all 56 known intermetallic phases with approximately 400 or more atoms per unit cell and space-group symmetry F43m, Fd3m, Fd3, Fm3m or Fm3c. Despite fundamental differences in chemical composition, bonding and electronic band structure, their complex crystal structures show striking similarities indicating common building principles. ...

The sizes of atomic groups are a fundamental aspect of protein structure. They are usually expressed in terms of standard sets of radii for atomic groups and of volumes for both these groups and whole residues. Atomic groups, which subsume a heavy-atom and its covalently attached hydrogen atoms into one moiety, are used because the positions of hydrogen atoms in protein structures are generally...

We explore how the atomic-scale structural and chemical properties of an oxide-supported monolayer (ML) catalyst are related to catalytic behavior. This case study is for vanadium oxide deposited on a rutile α-TiO2(110) single-crystal surface by atomic layer deposition (ALD) undergoing a redox reaction cycle in the oxidative dehydrogenation (ODH) of cyclohexane. For measurements that require a ...

Dislocations influence many properties of crystalline solids, including plastic deformation, growth and dissolution, diffusion and the formation of polytypes. Some of these processes can be described using continuum methods but this approach fails when a description of the structure of the core is required. To progress in these types of problems, an atomic scale model is essential. So far, atom...

The first real-space x-ray image of an atomic structure was obtained by illuminating a crystal with white synchrotron radiation. The internal photocurrent signal served as a probe of the x-ray interference field strength at the atomic sites and was accordingly measured as a function of illumination direction to record the two-dimensional image. This novel method of real-space imaging makes use ...

Arsenic is the chemical element that has the symbol As, atomic number 33 and atomic mass 74.92. Arsenic was first documented by Albertus Magnus in 1250.[4] Arsenic is a notoriously poisonous metalloid with many allotropic forms, including a yellow (molecular non-metallic) and several black and grey forms (metalloids). Three metalloidal forms of arsenic, each with a different crystal structure, ...

Human carbonic anhydrase II (HCA II) is a zinc-metalloenzyme that catalyzes the reversible interconversion of CO2 and HCO3-. The rate-limiting step of this catalysis is the transfer of a proton between the Zn-bound solvent molecule and residue His64. In order to fully characterize the active site structural features implicated in the proton transfer mechanism, the refined X-ray crystal structur...